1. Field of the Invention
The present invention generally relates to devices for adjustably occluding a fluid stream and more particularly relates to a damper assembly for a forced-air system employing a plurality of fanned blades to provide a regulated flow of air.
2. Description of the Prior Art
It has been known in residential and commercial heating, cooling, and ventilation systems to control temperature, humidity, and other environmental characteristics through regulation of air flow. Most commonly in forced-air systems, this takes the form of one or more dampers to control the volumetric flow rate in each of the conditioned spaces.
The most common damper assemblies utilize an air supply register having a circular or rectangular cross sectional bore, which is manually or electromechanically occluded using a baffle of appropriate geometry. In this form, the air supply bore is fully occluded when the plane of the baffle is placed perpendicular to the axis of flow of the air supply. Similarly, maximum air is supplied when the plane of the baffle is parallel with the axis of the air flow. Partial occlusion is accomplished as the baffle is manually or electromechanically rotated at angles between parallel to the air flow and perpendicular to it. Though this simplistic approach provides for manufacture using a small number of components, it produces an assembly which tends to require substantial clearance along the direction of the air flow. Thus, this approach is not useful for applications which do not have sufficient clearance.
One method of decreasing the required clearance parallel to the axis of air flow is to provide baffles which are essentially fixed. U.S. Pat. No. 1,449,583 suggests the use of static baffles. However, this design simply does not give the degree of control over environmental characteristics expected of modern systems.
Several approaches have been presented which offer a compromise between clearance and performance. U.S. Pat. No. 3,319,560, issued to Schaaf, shows a system employing flexible baffles. In this way, the required clearance is less and the performance is somewhat enhanced. However, this does represent a compromise and thus requires greater than minimal clearance and provides less than optimal performance.
Another type of compromise is shown in U.S. Pat. No. 3,068,891, issued to Panning et al. Using the Panning et al. technique, the bore is partially, but permanently, occluded with a plurality of fixed baffles and adjustably occluded with a plurality of rotatable baffles. This method provides a minimum of required clearance. However, because of the fixed baffles, the bore is at least partially occluded, even at maximum flow. Thus, performance is compromised.
U.S. Pat. No. 1,449,583, issued to Buck, utilizes a plurality of stacked discs. The discs are rotated into the bore to adjustably occlude the fluid flow. However, because of the manner in which the discs are used for baffling, the degree of occlusion cannot be easily and readily modified during operation.
A more elegant suggestion is made in U.S. Pat. No. 4,188,862, issued to Douglas, III. In this approach, a plurality of smaller occlusion baffles are stacked and adjustably spread in fan-like fashion coaxially within the fluid flow bore to achieve the desired amount of occlusion. The clearance requirement tends to be minimized, because the individual occlusion baffle elements are small in relation to the total cross sectional area of the fluid flow bore. However, performance can be optimized through the use of a relatively large number of relatively small surface area baffle elements necessitating a minimal occluded surface area during full output operation.
However, Douglas III does not address the key factors for providing an optimum and operable embodiment. As stated above, performance is enhanced with a larger number of smaller baffle elements. Yet this promotes additional flexure of the elements relative to one another. Such flexure tends to prevent complete occlusion and is most prominent between the upper most and lower most of the stacked baffle elements. Additionally, the relative movement of the baffle elements precludes accuracy of adjustment at varying pressures and prevents fully automated, precise operation.